1. Field of Invention
The present invention relates to a type of scanner and its internal memory access method. More particularly, the present invention relates to a scanner having synchronization dynamic random access memory (SDRAM) and its related memory access method.
2. Description of Related Art
At present, the most common type of memory to be used inside a scanner is dynamic random access memory (DRAM). Some high-grade scanners may use synchronization dynamic random access memory (SDRAM). Although a scanner that uses SDRAM performs image processing much faster than an ordinary scanner that uses DRAM, SDRAM scanners do have some defects that prevent a full utilization of their power.
In general, SDRAM use a burst transmission mode to access data. Hence, a large number of memory address transmissions using the data bus may be omitted and a large amount of data may be accessed at the same time. However, the digital signal processor (DSP) and the input/output (I/O) device inside a scanner employ a bit-by-bit data transmission mode. Hence, even when the scanner uses SDRAM as the memory for holding compensation data or images produced by an image processor, the high transmission speed possible for SDRAM in the burst mode is not realized.
Accordingly, one object of the present invention is to provide a scanner having synchronization dynamic random access memory (SDRAM) and its related memory access method. The SDRAM inside the scanner serves as a compensation memory for holding compensation data and as an image memory for holding processed images. A buffer capable of holding all the transmission data when the SDRAM operates in a burst mode operation is set up between the compensation memory and a digital signal processor (DSP), between an image processor and the image memory and between the image memory and an input/output device. By setting up buffers inside the scanner, SDRAM can fully utilize the available burst mode to increase the data access rate.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention provides a type of scanner that uses synchronization dynamic random access memory. The scanner includes an image processor, a compensation memory, an image archiving memory, an input/output device and a plurality of buffers. The image processor processes digital image signals. The compensation memory is a synchronization dynamic random access memory (SDRAM) for holding digital image signals processed by the image processor. The input/output device is connected to an external device for mutual data transmission. The plurality of buffers couples the compensation memory with the image processor, the image processor with the image archiving memory and the image archiving memory with the input/output device. Compensation data are transmitted to corresponding buffers in a burst mode and then relayed from the buffers to the image processor serially. The image processor relays the processed digital image signals to the corresponding buffers and then transmits the signals to the image archiving memory in a burst mode. Finally, the processed digital image data in the image archiving memory is transmitted to corresponding buffers in a burst mode and then relayed from the buffer regions to the input/output device serially.
This invention also provides a type of scanner with synchronization dynamic random access memory. The scanner includes a single cluster data access device, a synchronization dynamic random access memory (SDRAM) and a buffer. The single cluster data access device is able to access a cluster of data at a time. The SDRAM can transmit a plurality of data clusters in a burst mode of transmission. The buffer is coupled to the single cluster data access device and the SDRAM. The buffer transmits a single cluster of data to the single cluster data access device but transmits a plurality of data clusters to the SDRAM in a burst mode.
This invention also provides a memory access method for a type of scanner having a synchronization dynamic random access memory (SDRAM). The SDRAM is capable of transmitting a large volume of data every time a burst mode is executed. A buffer having the capacity to hold the data transmitted in a burst mode is provided. Data within the SDRAM is transmitted to the buffer in a burst mode. The data are next relayed from the buffer to the data devices that require the data serially.
This invention also provides an alternative memory access method for a type of scanner having a synchronization dynamic random access memory (SDRAM). The SDRAM is capable of transmitting a large volume of data every time a burst mode is executed. A buffer having the capacity to hold the data transmitted in a burst mode is provided. Data within a storage device is relayed to the buffer serially. The data stored within the buffer is transmitted to the SDRAM in a burst mode.
In brief, the SDRAM serves as compensation memory and image archiving memory inside a scanner. In addition, buffers each capable of holding at least a volume of data in a SDRAM burst mode transmission is provided. The buffers couple between the compensation memory and the image processor, between the image processor and the image archiving memory and between the image archiving memory and the input/output device. With this setup, the burst mode of the SDRAM can be fully utilized to increase the operating speed of the scanner.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.